In the Trojan War Xanthus and his brother, Balius, were the horses who pulled Achilles chariot. It is stated that Achilles best friend, Patroclus, was the only person to fully control them and Achilles allowed him to ride into battle with them. Achilles warned Patroclus not to go too far into battle and Patroclus ignored him and ended up getting killed. Xanthus and his brother grieved for his death and soon after given the power to speak [no one really knows which god]. The god that gave him these powers told him to go tell Achilles that Patroclus was killed by a god that so would he. Achilles rebuked the horses for not protecting when told Patroclus was killed and upon Xanthus finishing his message he was then struck dumb.